https://gcc.gnu.org/bugzilla/show_bug.cgi?id=39440
--- Comment #5 from David <gccbugzilla at limegreensocks dot com> --- This is a duplicate of 30527. A subset of the most commonly needed/used modifiers have been added to the docs as of 5.x (including the %c0 referenced above). For this reason, I recommend this bug be closed. If there is some additional modifier that you need, I'd recommend opening a new bug and making an explicit case for it.
